PSIV-6 Impact of Cooling Pads and Dietary Moringa on Measures of Heat Stress in Sows in Late Gestation

Abstract Gestating sows become more sensitive to high temperatures at the end of gestation. Cooling pads have been developed that reduce the impact of high environmental temperatures on sows. Some of the added heat stress response may be due to oxidative stress which might be reduced with dietary antioxidants. The objective of this study was to evaluate the daily patterns of common measures of heat stress on late gestation sows with or electronic cooling pads (ECP) with or without the addition of Moringa, a plant with antioxidant activity. Sows (n = 24), 2 days before farrowing, were assigned a 2 × 2 factorial arrangement of treatments: farrowing crates with or without cooling pads and corn-soybean based diets containing either 0 or 4% Moringa leaf powder. Sows were fed 1.36 kg of feed twice a day and had ad-libitum access to water. The farrowing room was targeted to have a 32°C daytime from 1100 to 1700 h and 26°C nighttime). The ECP flushed 2.0 L of cool water when one of the three temperature sensors reached 26°C. Skin temperature (TS) was measured hourly using an infrared gun 10 cm behind the ear, and hourly respiration rate (RR) recorded from 600 to 2200 h. Rectal temperatures were (TI) taken at 600, 1300, 1600 and 1900 h. Two statistical analyses were conducted. The first was a mixed model including the fixed effects of ECP, diet, hour of measurement and their interactions with sow included as a random effect. Also, mixed model periodic regressions were fitted to the RR and TS data. The RR was impacted by ECT, hour, and ECP × hour interactions (P < 0.001). The final model for RR included the random effect of sow, main effect of ECP, single phase sine/cosine and 2-phase cosine variables and the interaction with the single-phase variables with ECP treatment (P < 0.001). For TS, there was only a tendency for the ECP treatment (32.4 vs. 33.0°C, P = 0.064) and effect of hour of measurement (P < 0.001) The final model for TS using periodic regression included the random effect of sow, ECP treatment (P = 0.12), single-phase sine and cosine and two-phase sine variables (P < 0.001) and interaction of single-phase sine variable by ECP treatment (P = 0.024). Overall ECP reduced internal temperatures by 0.23°C (P = 0.17) with trend for a ECP × time interaction (P = 0.074) with the greatest impact at 1300 h (38.04 vs. 37.53, P < 0.02). The ECP produced greater relative reductions in RR and smaller differences in TI. Daily mid- to late- afternoon increases in RR,